The electrochemistry of alkoxylated arylene vinylene oligomers: Oxidation potentials and diffusion coefficients

Self‐doping PPV oligomers – electrochemistry and structure of the self‐doped systems

“…In accordance with our previous study on non‐self‐doping PPV oligomers,3 an electrochemical characterisation of these new oligomers was also performed. Due to the absence of a reduction peak in the voltammogram, the formal oxidation potentials could not be determined,23–26 but the anodic peak potentials are reported.…”

“…Due to the absence of a reduction peak, the formal oxidation potentials, E °, could not be determined; the anodic peak potentials, E pa , have been presented in Table 1. It is important to note that these measurements were performed under the exact same conditions as for the non‐self‐doping oligomers from our previous work,3 complete with added supporting electrolyte, in order to facilitate the evaluation of the influence of the self‐doping substituent. In our opinion, the absence of the reverse peaks is most likely due to a follow‐up chemical reaction, in particular the formation of the self‐doped complex (see section 3.2), rather than to the irreversibility (or semi‐reversibility) of the redox process; the electron transfer processes of 4a – e are in fact similar to those of their non‐ionic (non‐self‐doping) counterparts 3.…”

“…It is important to note that these measurements were performed under the exact same conditions as for the non‐self‐doping oligomers from our previous work,3 complete with added supporting electrolyte, in order to facilitate the evaluation of the influence of the self‐doping substituent. In our opinion, the absence of the reverse peaks is most likely due to a follow‐up chemical reaction, in particular the formation of the self‐doped complex (see section 3.2), rather than to the irreversibility (or semi‐reversibility) of the redox process; the electron transfer processes of 4a – e are in fact similar to those of their non‐ionic (non‐self‐doping) counterparts 3. In order to verify this statement, measurements were performed at elevated scan rates to make the reduction peak appear, but these attempts were unsuccessful due to the predominant effect of ohmic drop under these conditions.…”

“…Due to the absence of a reduction peak in the voltammogram, the formal oxidation potentials could not be determined,23–26 but the anodic peak potentials are reported. Analogous to our previous report, these peak potentials have been correlated with adiabatic ionisation potentials, readily obtained from the quantum chemical calculations 3. Diffusion coefficients, easily extracted from electrochemical data, could also not be determined since no suitable solvent for the entire series could be found.…”

“…The neutral oligomers are electrical insulators, but it has been shown3 that they can be conveniently oxidised electrochemically and deposited as electrically conducting radical‐cation salts, after incorporation of an anion from the supporting electrolyte in the electrochemical cell. After questions had been raised about the purity of these doped oligomers, in particular with regard to the amount of supporting electolyte that is incorporated during the deposition, the possibilities of eliminating the supporting electrolyte from the electrochemical set‐up were investigated.…”